1. Field of the Invention
The invention relates to a natural environment simulation apparatus for controlling biological responses, in particular, to an artificial lighting apparatus functioning by simulating full spectrum sunshine for developing biological growth.
2. Description of Related Art
The plants are capable of capturing photon energy to perform photosynthesis which supports the living beings on earth. In addition, plants also contain photon capture apparatus called photoreceptors which response to different wavelengths of lights and control growth and development of plant. The most well known phtoreceptor is phytochrome which responds to red light and far-red light in regulating many important physiological responses including the germination of seeds and controlling the time of flowering. The phytochromes have two forms PR (which absorbs red light) and PFR (which absorbs far-red light). Many plant physiological responses like flowering and germination of seed are reversibly controlled by shinning red light and far-red light. This photoreversibility is caused by the interconvertability of the two forms PR and PFR. Additionally, some plants growth is influenced by the length of day and night, i.e., called as photoperiodism. The photoperiodism is used to regulate the formation and quantity of phytochrome within the plants and to set circadian rhythms.
In the genetic sequencing of CRY1 gene and the following studies, another short wavelength photoreceptor is cryptochrome has been discovered, which also controls Arabidopsis thaliana stem elongation, folia unfolding, photoperiod flowering, and other biological clock response. In addition, a blue light photoreceptor phototropin has been correlated with phototropism. In nature, these different wavelengths of lights are composed as one and expressed as different color temperatures followed by the sunrise from the east and set to the west. The traditional artificial lighting and growth chamber cannot change of light angles and color temperatures in the continuous way just as the sun does. This makes it difficult to study and control the plant growth and development through these photoreceptors in the nature sun or simulate the sun fashion.
Please refer to Taiwan Patent No. M323194, “Multifunctional light emitting diode plant cultivation lamp for promoting growth rate”, which is characterized in that the ratio of composition for light emitting diode (LED) materials is capable of being modified, so that the LED can be a light source which may produce different wavelengths and light colors. Hence, a multi-bandwidth light tube made by the LEDs is utilized to produce a certain amount of light at a specific wavelength incident on the plants, thereby controlling the plants growth per requirements.
Yet, the conventional multifunctional light emitting diode plant cultivation lamp for promoting growth rate has deficiencies as following:
First, the multi-bandwidth light tube is composed of a variety of LEDs with different wavelengths which is assembled into a specific order. Because the light emitting from the multi-bandwidth light tube is not entirely suitable for plants growth, and it does not take phytochrome, cryptochrome, phototropin, and photoperiod into considerations, the plant growth promotion is limited.
Second, it is unable to simulate natural sunlight for achieving a control over a light angle and a color temperature gradually, such that plant growth and flowering control is not precise.